Expansion-bolt.



L. R. ZIFFERER. EXPANSION son. 7

I I APPLICATION FILED NOV. 25, 1914. 1,136,638

E2 Mani/7" joffiarii, Zz'fferer Patented Apr. 20, 1915.

UNITED STATES PATENT OFFICE.

LQTHAR R. ZIFFERER, OF NEW YORK, N. Y.

EXPANSION-BOLT.

Specification of Letters Patent.

Patented Apr. 20, 1915-.

Application filed November 25, 1914. Serial No. 873,967.

with the exterior construction of the shield. I

one'of its principal -";1fih'eanner end.

. Itdwi'll I e noted that between the threads My invention has for ob ects the provision of elements upon the shield exterior so formed, arranged, and

- proportioned as to facilitate insertion of the device into its intended aperture, to resist withdrawal from the aperture, and prevent rotary movement within the aperture.

Other objects and uses willalso appear from a detailed description of the invention as hereinafter set forth. I

It is well recognized that there are many materials in which expansion bolts are commonly anchored. Also it is common knowledge that the walls of the holes drilled to receive such expansion bolts are not invariably sn-iooth and free from irregularities. For these reasons it is frequently diflicult to insert anexpansion bolt into operative position. although the hole drilled for the purpose may appear to be of the proper dimelr sion. This is due often to slight projections or other irregularities remainingupon the, face of the wall wlnch surrounds the hole.

I have provided the construction shown herein to facilitate the insertion of an expansion bolt, as well from turning within, the aperture.

In the drawing: Figure 1 is a side elevation of an expansion bolt embodying my invention, shown inserted within an aperture for the greater portion of its length; Fig. 2 is an end elevation of the device as shown in Fig. 1, looking toward the aperture; Fig. 3 is a side elevation of the expansion bolt shown completely inserted within an aperture; and Fig. 4 is an end elevation of the device as shown in Fig. 3, looking toward the aperture.

In the drawing I have represented a onepiece shield 5 slotted for the greater portion of its length to provide expansible segments 6, the outerjor collar end 7 being integral.

as to prevent the same or withdrawing from,

' disposed -vaneement brought Arranged upon the exterior of the shield for the greater portion of its length", are spiral threads 8 of a size and pitch to pro? vide between them spaces of substantial width. At the outer end of the shield body I arrange a number of projections or ribs 9, preferably in directions parallel with the axis of the shield,- and extending above the body of the shield slightly higher} than the threads 8. Expansion of the shield is brought about in the usual manner as by advancing a bolt or screw into the shield interior, which is customarily tapered toward formed upon the'shield exterior are spaces of substantial width. This is for the purpose of providing suflicient clearance within which may lie projections or other irregularities on the walls of the aperture, to permit of the shield being freely advanced into position through a rotary movement. It is desirable that the shield be inserted as far as possible by a frictionless -method, rather than through a forcible advancement which would tend to break down and destroy the spiral. threads that are of the same degree of ductility as the material of which the shield body is formed. To assist in this threading action, I prefer to employ a pill rality of outer end projections 9, such as the number six which are shown on the draw ing, by which a convenient hold is provided for the operators fingers or for an instrument, if it be necessary, to impart rotary movement to the shield.

It is apparent when the inserted within the aperture up to the point where the longitudinal projections are located, a positive resistance is offered against further inward movement. To overcome this,.I contemplate the application of force as by the striking of a blow against the outer end of the shield to advance the same the necessary distance to bury the device comp "tely within the aperture. This adabout under pressure results in a jamming or breaking down of the projections 9, such as to flatten out the llltlr terial composing the same against the sides of the hole to efl'ect a tight fit. As a result of such operations, it will be found that the shield when completely inserted in thc aperture is so firmly wedged in place as to of lectually resist any tendency toward rotation when a screw or bolt is inserted for shield has been purposes of expansion. It is very desirable that no considerable friction between the shield and aperture should develop when the shield is first inserted.v As previously explained, interference to an easy insertion,

. due to resistance offered by uneven and irregular places on the aperture Walls, may be eliminated to a large extent if threads on the shield exterior enable rotation in the manner described. Without such a construction a hammer blow might often be required at the beginning of insertion. Until the shield has been inserted Well Within the hole, 110 such hammer blow should be struck, as, under such circumstances, a soft metal shield willfrequently bend or buckle unless it is reinforced for a considerable portion of.

its length by the walls of a surrounding aperture. It frequently happens moreover that a number of shield threads at the inner end of the shield areworked past the irregular and uneven places on the aperture walls,

so that'when the shield is eventually struck to complete its insertion, such threads will not be broken down or otherwise mutilated so as to be rendered less effective for resisting forces which tend to withdraw the shield from the aperture. I prefer to use several of these longitudinal ribs to assist in the wcdging action described. It is desirable that the cross sectional area of these projections should beso proportioned with respect to the intervening spaces as to allow of a spreading and flattening out of the material composing the same suilicient to effect the desired wedging pressure. For this purpose, as well as to multiply the number of flopies of this patent may be obtained for places atwhich such a wedging pressure is applied, I have shown six ribs 9, although the same wedging results, though in a "less degree, are obtainable by varying this numher. It will be noted also that for reasons of expediency in manufacture, I have caused the spaces between the ribs on the shield body adjacent the slots separating the segments 6 to be slightly greater than the other distances intervening between the ribs, and that the said ribs adjacent the slots are somewhat inclined toward these enlarged":

spaces. This is for the purpose of causing such ribs when pressed into the aperture to break down and flatten out in the direction the outer. end with projections slightly higher than the threads, s'aid projections be 'ing irregularly spaced apart and inclined toward the wider adjacent spaces, substantially as described.

a LOTHAR R. ZIFFERER.

Y Witnesses: v

P. FRANK SONNEK, H. E. CHAMPION.

five cents each, by addressing the Commissio of Patents, Washington, D. G. 

